As information technology develops, a display device which connects a user with information has become more important. Examples of the display device may include flat panel displays such as an organic light emitting display device and a liquid crystal display device.
A display device includes a display panel that comprises a plurality of pixels disposed in a matrix pattern and a driving unit for driving the pixels. The pixels may be divided into red, green, and blue sub-pixels in order to realize colors. A white sub-pixel may be added if necessary. Each of the sub pixels is connected to one of a plurality of scan lines and one of a plurality of data lines provided in the display panel. The driving unit includes a scan driver for supplying a scan signal to the scan lines disposed in a display area and a data driver for supplying a data signal to the data lines. Upon receiving the scan signal via the scan line, the sub-pixels are charged with the data signal supplied from the data line, and emit lights according to the data signal to display an image.
The scan drive can be configured with a plurality of integrated circuit (IC) chip mounted in the non-display area of the display panel. However, IC chip makes it difficult to reduce the bezel size of the display device. Accordingly, use of the IC chip as the scan driver is to be avoided, and instead, the scan driver should be provided in a Gate-In-Panel (GIP) structure implemented with thin-film-transistors disposed in the non-display area on the display panel. The scan driver includes a shift register 140. The shift register 140 includes a plurality of stages that are arranged to shift a scan signal in reference to a predetermined clock signal and output scan signals on the scan lines. For each frame of image data to be displayed on the display area, the scan driver outputs a scan signal sequentially from the first scan line to the last scan line of the display panel.
Recently, as the application fields of the display device have expanded, the display device displays various kinds of images. Many features that were once provided in a physical form are now provided as an interactive graphical interface displayed on the screen of the device. For example, physical buttons of many electronic devices are being replaced by graphical buttons, which a user can interact via touch screens.
Type of contents to be displayed by the display device have also been advanced, and many different types of image contents are simultaneously presented on the screen. For instance, a video may be displayed in a part of a screen while another part of the screen displays a still image (ex. a text or a picture). Accordingly, it would be desirable if the refresh rate of pixels in a selective region of the screen can be adjusted differently from other regions of the screen. Similarly, it would be desirable to temporarily pause and resume driving of a selective region of the screen without interrupting the driving of other regions of the screen. In other words, only some of stages corresponding to a specific area of a screen may be partially driven, or stages corresponding to a certain area may be differently driven from stages corresponding to another area. In this way, power consumption can be reduced or a noise caused by output of scan signals can be reduced to improve performance of the display device in many ways. However, a typical scan driver is configured to output a scan signal sequentially from the first stage to the last stage, each corresponding to the first scan line to the last scan line of the display area. Thus, it is difficult to control a selective regions of the screen differently from other regions of the screen.